This proposal is concerned with the assessment of vitamin A nutriture and the effect of disease on vitamin A metabolism. The work proposed is divided into 3 major projects: I. Development of a rapid noninvasive visual test to functionally screen for vitamin A deficiency; The specific aims of this section are to determine the: 1. Strength of the correlation between the final dark adapted threshold, rod cone break time, and the rapid dark adaptation test time in normal subjects and diseased patients. 2. Sensitivity and specificity of the rapid test for vitamin A deficiency. 3. Reversibility to normal of the rapid dark adaptation test by vitamin A therapy into vitamin A deficient individuals. II. Assessment of the effect of protein deficiency on vitamin A metabolism and utilization in chronically ill patients and animals; The specific aims of this experiment are to determine: 1. Effectiveness of a) vitamin A therapy alone, or b) protein repletion in reversing abnormal dark adaptation in patients who are both vitamin A and protein depleted. 2. Effect of vitamin A replenishment on the retinyl ester content in blood in patients who are both vitamin A and protein depleted. 3. Effect that protein depletion has on the electroretinogram of the rat. 4. If the vitamin A and protein depleted rat can respond to vitamin A replenishment alone with return of the electroretinogram to normal. 5. Effect of protein depletion on the expected rise in serum retinol after a low dose vitamin A challenge in vitamin A deficient patients. 6. Effect of protein depletion on serum retinyl ester levels after a low dose of vitamin A challenge in vitamin A deficient patients. III. Assessment of the effect of disease and protein deficiency on the gastroitestinal absorption of new vitamin A preparations (acasia or gel sealed), which are currently being used in fortification programs. All of our studies are aimed at providing better vitamin A nutriture to the chronically ill.